• Atmosphere
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• v.16 no.4
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• pp.359-370
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• 2006

Terrain height variance spectra for the Korean mountain region are calculated in order to determine an adequate grid size required to resolve terrain forcing on mesoscale model simulation. One-dimensional spectral analysis is applied to specifically the central-eastern part of the Korean mountain region, where topographical-scale forcing has an important effect on mesoscale atmospheric flow. It is found that the terrain height variance spectra in this mountain region has a wavelength dependence with the power law exponents of 1.5 at the wavelength near 30 km, but this dependence is steeply changed to 2.5 at the wavelength less than 30 km. For the adequate horizontal grid size selection on mesoscale simulation two-dimensional terrain height spectral analysis is also performed. There is no directionality within 50% of spectral energy region, so one-dimensional spectral analysis can be reasonably applied to the Korea Peninsula. According to the spectral analysis of terrain height variance, the finer grid size which is higher than 6 km is required to resolve a 90% of terrain variance in this region. Numerical simulation using WRF (Weather Research and Forecasting Model) was performed to evaluate the effect of different terrain resolution in accordance with the result of spectral analysis. The simulated results were quantitatively compared to observations and there was a significant improvement in the wind prediction across the mountain region as the grid space decreased from 18 km to 2 km. The results will provide useful guidance of grid size selection on mesoscale topographical simulation over the Korean mountain region.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.E
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• pp.390-396
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• 1993

An acid deposition Engineering Model was developed by parameterizing the role of organics in the photochemistry and by simplifying liquid phase processes. This Engineering Model concept was implemented onto the Sulfur Transport Eulerian Model II(STEM II). The Engineering Model version of the STEM(STEM-ENG) saves the CPU time over 50 times and produces the upper and lower limit values prodicted by the original STEM II. These limits obtained by the STEM-ENG can be used to estimate the importance of organics in acid and O3 production. The STEM-ENG with 30,000 grid points can be run on any recent PCs to give a quick assessment of air quality.

• Journal of Korean Society for Atmospheric Environment
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• v.3 no.1
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• pp.47-54
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• 1987

A new method for designing air pollution monitoring newtork is presented in this study. In this method, the magnitudes and the correlation coefficients of predicted concentrations in each grid points are examined and the monitoring stations are assigned to those stations which cover the damage cost the most. This method was applied to the Ulsan-Onsan Industrial Complex. This method turned out to be much more efficient than the method of TM coordinates and the method of concentric circles prescribed in the Standard Methods for Pollution Measurement as well as the existing monitoring system established in the area. The 21 stations selected by the method of TM coordinates could cover only 64.4% of the damage cost in the area, the 16 stations by the method of concentric circles 72.1%, and the existing 21 stations 67.8%, while 11 stations were enough to cover 90% of the damage cost in the area with this method. It also was found that this method required only 24 stations to cover the entire area.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.2
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• pp.89-95
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• 1991

Yellow sands often occur in Korea during April and May each year, and they are believed to come from the Mongolian Gobi desert as the snow starts to melt in Spring time. Since the analysis of aerosol particulates can hardly distinguish the origin of particulates, the isentropic analysis of meteorological data is often used for the trajectories of the long range transport of yellows sand or air pollutants. The yellow sand case of April 9 $\sim$ 15, 1988, in Korea is analyzed for the identification of long range transport of yellow sands and their trajectories in East Asia, using isentropic analyses. We have tranformed the ECMWF grid data, analyzed in pressure coordinates, into the isentropic coordinates and then have traced the 286 K and 290 K air mass which started Gobi desert. The result shows the transport of yellow sands from the Gobi desert to the Korean peninsula.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.5-9
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• 2010

A numerical wind tunnel simulation is performed in order to predict wind loads acting on a building. The aim of the present study is to suggest a guideline for the numerical wind tunnel analysis, which could provide more detail wind load distributions compared to the wind code and expensive wind tunnel experiments. To validate the present numerical simulation, wind-induced loads on a 6 m cube model is predicted. Atmospheric boundary layer is used as a inlet boundary condition. Various effect of numerical methods are investigated such as size of computational domain, grid density, turbulence model and discretization scheme. The appropriate procedure for the numerical wind tunnel analysis is suggested through the present study.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.223-233
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• 1999

The wind-flow characteristics over a two-dimensional triangular prism with a porous windbreak are numerically investigated. The geometry is a simplified model of large outdoor stack with a frontal wall-type windbreak which is used to prevent particle dispersion by reducing wind speed over stak surface. In the present numerical model, the RNG k-$\varepsilon$ model, the orthogonal grid system and the QUICK scheme are employed for the successful simulation of separated flow. The predicted results are compared and validated with the associated wind-tunnel experiments. In addition, the trajectories of dispersed particles and their sedimentation characteristics are quantitatively investingated using a Lagrangian turbulent-dispersion model.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.E
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• pp.347-357
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• 1993

The Lagrangian grid-free numerical method, the discrete vortex method, was applied to solve the Navier-Stokes euqations. This method avoids the introduction of numerical viscosity swamping the real physical viscosity at high Reynolds number, unlike Eulerian method, e.g. finite difference and element methods. The boundary integral equation method for the potential flow solution was included to make the discrete vortex method more feasible for complex geometries. The fast adaptive multipole expansion method was incorporated to reduce the computational time from $O(N^2)$ to O(N) for the computations of vortex-vortex interactions. The test problems were air flow around one circular cylinder and two circular cylinders in tandem with various gaps. The numerical results were in excellent gareement with the experimental and other computational results. The applicabilty of the method was discussed with the indoor and the outdoor air pollution problems, especially the contaminant transport in the recirculation regions.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.E
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• pp.45-54
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• 1999

The effectiveness of NOx emission reductions from power plants to alleviate persistent ozone nonattainment in the esterm Unites States was investigated with a focus on the Northeast Corridor, centered on New York City. The 1995 ozone episode along with the 2007 base case emission scenario was used with the Variable-Grid Urban Airshed Model(UAM-V) to determine ozone concentrations. Several scenarios based on EPA's proposal issued on October 10, 1997 were examined. Although it is widely recognized that the eastern United States includes a large Nox-sensitive region(e.g., Sillman, 1999), the study revealed that reducing NOx emissions from power plants beyond 500 miles (800km) was not effective for reducing ozone exceedances in the region. It was also found that NOx emissions from power plants play an important role in local ozone exceedances.

• Journal of Environmental Science International
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• v.8 no.6
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• pp.645-652
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• 1999

In order to simulate and investigate the major characteristics of El Nino/Southern Oscillation(ENSO) and Madden Jullian Oscillation(MJO), an intermediate type atmosphere-ocean coupled model is developed and their results are examined. The atmosphere model is a time-dependent non-linear perturbation moist model which can determine the internal heating for itself. The counterpart of the atmosphere model is GCM-type tropical ocean model which has fine horizontal and vertical grid resolutions. In the coupled experiment, warm SST anomaly and increased precipitation and eastward wind and current anomalies associated with ENSO and MJO are properly simulated in Pacific and Indian Oceans. In spite of some discrepancies in simulation MJO, the observed atmospheric and oceanic low-frequency characteristics in the tropics are successfully identified. Among them, positive SST anomalies centered at the 100m-depth of tropical eastern-central Pacific due to the eastward advection of warm water and reduced equatorial upwelling, and negative anomalies in the Indian and western Pacific seem to be the fundamental features of tropical low-frequency oscillations.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2016.09a
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• pp.25-28
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• 2016

Recently, because of the weather forecasts through the low-resolution data has been limited, the demand of the high-resolution data is sharply increasing. Therefore, in this study, we restore the ultra-high resolution synthetic precipitation and temperature data for 2000-2014 due to small-scale topographic effect using the QPM (Quantitative Precipitation Model)/QTM (Quantitative Temperature Model). First, we reproduce the detailed precipitation and temperature data with 1km resolution using the distribution of Automatic Weather System (AWS) data and Automatic Synoptic Observation System (ASOS) data, which is about 10km resolution with irregular grid over South Korea. Also, we recover the precipitation and temperature data with 1km resolution using the MERRA reanalysis data over North Korea, because there are insufficient observation data. The precipitation and temperature from restored current climate reflect more detailed topographic effect than irregular AWS/ASOS data and MERRA reanalysis data over the Korean peninsula. Based on this analysis, more detailed prospect of regional climate is investigated.